The new Sellwood Bridge has a steel deck arch design, with three arches supporting the deck of the main river spans. The new bridge is 1,976 feet long, including the main river spans and the east and west approaches. The three main river spans alone are 1,275 feet long.
Why a Steel Deck Arch?
A steel deck arch design was recommended by the Community Advisory Committee and confirmed by the Board of County Commissioners. Benefits of the design that were noted include:
- Arched form fits the natural setting
- Appropriate to neighborhood scale
- Open steel structure echoes character of the first bridge
- Top-ranked bridge type in public on-line survey
- Adds to city's unique bridge collection
- Can be built within the established budget
- Has high technical performance
- Sustainable – components are made of recycled steel
- Provides employment opportunities for local firms to build
The Locally Preferred Alternative
The Locally Preferred Alternative, selected in 2009, determined that the new Sellwood Bridge would:
- Be built in its current alignment and widened 15 feet to the south to allow for continuous traffic flow during construction
- Be 64 feet at a cross-section of its narrowest point: two 12-foot travel lanes, two 12-foot shared use sidewalks, and two 6.5-foot bike lanes/emergency shoulders
- Include a grade-separated and signalized interchange at the OR 43 (SW Macadam Avenue) intersection on the west end
- Include a pedestrian-activated signal at the intersection of SE Tacoma Street and SE 6th Avenue on the east end
- Be consistent with the Tacoma Main Street Plan
- Restore bus and truck traffic; and accommodate possible future streetcar
Extensive public outreach occurred during the selection of the Locally Preferred Alternative to ensure that the public was involved in the process in a meaningful way.
After the planning process was complete, including the necessary approvals from state and federal agencies, Multnomah County and its partners sought to reduce the project costs and shrink the overall footprint, particularly at the west end connection with Highway 43. Planners succeeded in trimming the project back and reducing environmental impacts while maintaining multimodal functionality, safety and traffic performance.
Refinements made to the Locally Preferred Alternative, approved by the Multnomah County Board of Commissioners in 2011, include:
- Compressed interchange design that saves money and shifts project away from hillside
- Reduction in size of the west end rock cut by 50% (40 feet high rather than 80 feet high)
- Alignment revision to accommodate future streetcar at a safer location
- Bicycle/pedestrian spiral ramps replaced with switchback ramps
- Less impact to Riverview Cemetery